Which Statement Is True About the Plasma Membrane

Which statement is true about the plasma membrane?

A) The proteins make up the matrix of the membrane.
B) The model can be likened to a sandwich where phospholipids are like the bread and proteins are like the filling.
C) The fluid nature of the membrane is regulated by flip-flopping of the phospholipids from one side of the membrane to the other.
D) The movement of proteins and phospholipids can occur sideways within the plane of the membrane.